[ndnSIM] fw: Keep both the CS of NFD and ndnSIM

Ref: #2231
diff --git a/daemon/fw/forwarder.cpp b/daemon/fw/forwarder.cpp
index 7e5d883..300dbc8 100644
--- a/daemon/fw/forwarder.cpp
+++ b/daemon/fw/forwarder.cpp
@@ -91,9 +91,20 @@
   const pit::InRecordCollection& inRecords = pitEntry->getInRecords();
   bool isPending = inRecords.begin() != inRecords.end();
   if (!isPending) {
-    m_cs.find(interest,
-              bind(&Forwarder::onContentStoreHit, this, ref(inFace), pitEntry, _1, _2),
-              bind(&Forwarder::onContentStoreMiss, this, ref(inFace), pitEntry, _1));
+    if (m_csFromNdnSim == nullptr) {
+      m_cs.find(interest,
+                bind(&Forwarder::onContentStoreHit, this, ref(inFace), pitEntry, _1, _2),
+                bind(&Forwarder::onContentStoreMiss, this, ref(inFace), pitEntry, _1));
+    }
+    else {
+      shared_ptr<Data> match = m_csFromNdnSim->Lookup(interest.shared_from_this());
+      if (match != nullptr) {
+        this->onContentStoreHit(inFace, pitEntry, interest, *match);
+      }
+      else {
+        this->onContentStoreMiss(inFace, pitEntry, interest);
+      }
+    }
   }
   else {
     this->onContentStoreMiss(inFace, pitEntry, interest);
@@ -288,7 +299,10 @@
   }
 
   // CS insert
-  m_cs.insert(data);
+  if (m_csFromNdnSim == nullptr)
+    m_cs.insert(data);
+  else
+    m_csFromNdnSim->Add(data.shared_from_this());
 
   std::set<shared_ptr<Face> > pendingDownstreams;
   // foreach PitEntry
@@ -341,7 +355,10 @@
   bool acceptToCache = inFace.isLocal();
   if (acceptToCache) {
     // CS insert
-    m_cs.insert(data, true);
+    if (m_csFromNdnSim == nullptr)
+      m_cs.insert(data, true);
+    else
+      m_csFromNdnSim->Add(data.shared_from_this());
   }
 
   NFD_LOG_DEBUG("onDataUnsolicited face=" << inFace.getId() <<